8. Castillo de Bellver (79 million gallons) -- On August 6, 1983, a fire broke out aboard the Spanish tanker Castillo de Bellver, causing a massive explosion and oil spill off the coast of South Africa.

7. ABT Summer (80 million gallons) -- The Liberian supertanker ABT Summer exploded off the coast of Angola on May 28, 1991, killing five crew members. Millions of gallons of oil leaked into the Atlantic Ocean.

6. Nowruz Oil Field (80 million gallons) -- On February 10, 1983, at the height of the Iran-Iraq War, an oil tanker collided with the Nowruz platform in the Persian Gulf. The slick caught fire when Iraqi planes attacked.

5. Fergana Valley (88 million gallons) -- In March 1992, oil spilled from a well in Fergana Valley, a densely populated industrial and agricultural zone in Uzbekistan. The incident remains the largest inland oil spill in history.

4. Atlantic Empress/Aegean Captain (90 million gallons) -- On July 19, 1979, two gigantic supertankers collided off the Caribbean island of Little Tobago during a tropical rainstorm. The accident killed 26 crew members and dumped millions of gallons of crude oil into the sea.

3. Ixtoc (140 million gallons) -- The exploratory oil well Ixtoc I exploded in the Gulf of Mexico on June 3, 1979, spewing 140 million gallons of oil into the open sea.

2. Deepwater Horizon (206 million gallons) -- An explosion on the Deepwater offshore rig killed 11 BP workers and spilled hundreds of millions of gallons of oil into the Gulf of Mexico over several months in 2010.

1. Gulf War Oil Spill (240 million gallons) -- In January 1991, Iraqi forces deliberately released more than 240 million gallons of crude oil into the Persian Gulf in an attempt to thwart an amphibious landing by the U.S. Marines.